Most patterns for these have long since been taken off the web. There are a few different names for the stitches they were used for. Annie's Attic calls it Crochet on the Double. Other people call it "Cro-Hook" or "Crochenit". Here is one site with a few free patterns that use double ended hooks:
http://www.crochetkim.com/catalog/crohoo…
Only the first pattern would require a circular crochet hook.
You will find some patterns here too:
http://www.crochenit.com/free_patterns.h…
They were designed for the hook that is only sold on this site (it's just a large double ended hook). You can do them with either a double ended crochet hook or circular crochet hooks. Be sure and nose around that website a bit, they like people to use the technique called the "bedspread stitch", but it's not necessary.
You can also do Tunisian stitch (aka afghan stitch) project with circular crochet hooks. I am working on one right now actually.
Here are a few more sites (some are for Tunisian crochet):
http://www.crochetpatterncentral.com/dir…
http://www.crochetpatterncentral.com/dir…
http://hmmmk.tripod.com/Crohook.htm
http://www.marloscrochetcorner.com/croch…
http://kimguzman.bravejournal.com/entry/… (scroll down to see what she says about the difference between Tunisian and Cro-Hook stitches.)
~Happy Crocheting!~